Kiwi researchers work on biodegradable metal implants

Biodegradable metal plates and screws could be used to save patients from undergoing further surgeries after their head or facial fractures have healed if Kiwi research is successful.

University of Canterbury's Dr Mark Staiger is working on a biodegradable metallic alloy that would break down safely in the human body, eliminating the need to reopen a wound to remove a metal plate or screw once a broken bone has healed.

"During its lifetime, an implant that is intended to temporarily assist the healing of a bone will transition from an implant to a foreign body, once the body has healed itself.

"A major driver of this research is the cost-effective removal of this foreign body by having it biodegrade after having completed its role in bone healing," the mechanical engineer said.

Titanium is currently used to fix damaged bones, partly because it is thought to resist corrosion in the body.

Dr Staiger is experimenting with magnesium to develop parts which would not be harmful to humans.

"Along with collaborators from Otago University, we are developing degradable magnesium plates and screws that will improve hospital costs and patient outcomes, representing a paradigm shift in the current technology.

"This new approach will deliver reduced patient recovery time by enhancing new bone formation and reduce cost by eliminating the need for secondary surgery to remove implants," he said.

Based on the number of plates used annually at Dunedin hospital and the cost of maxillofacial surgery, he estimates that plate removal alone costs the New Zealand health system $12 million a year.

"World-wide the total costs are staggering," he said.

His research is also aimed at fixing problems associated with the current metal devices, such as growth restriction, bone resorption due to stress shielding, and infection.

"Rigid titanium-based plates or screws have gained widespread acceptance in correcting head deformities and in the management of fractures in the last two decades. However, 50 per cent of all titanium plate systems require removal.

"A temporary biodegradable implant would eliminate the need for surgical removal of the implant. Our previous work on the breaking down of magnesium alloys has shown their potential as a new degradable implant material."

Dr Staiger and his team are hoping to work with device manufacturers to help develop such biodegradable implants in the long term.